Apparatus for pulling drill pipe

ABSTRACT

Apparatus for pulling drill pipe has four hydraulic legs which extend and retract surface engaging feet to raise and lower a frame. A drill pipe gripping mechanism is mounted to the frame and comprises a slip bowl with an inner surface tapering inwardly and downwardly and a plurality of wedge-shaped slips which have one surface tapered to engage the inner surface of the slip bowl and the other surface parallel to the axis of the slip bowl. The slips slide down to engage a drill pipe surface and the hydraulic legs are extended to pull the pipe upwards. A control ring is mounted to the frame for limited axial movement and connecting members connect each slip to the control ring. A plurality of smaller hydraulic cylinders are connected between the frame and the control ring so that when these cylinders are extended the control ring is raised to pull the slips upwardly and thus ensure the slips disengage the surface of the drill pipe before the four hydraulic legs are retracted for the next cycle.

United States Patent 1 Becker 1 1 APPARATUS FOR PULLING DRILL PIPE [75] Inventor: Floyd W. Becker, Calgary, Canada [73] Assignee: Drill Systems 1nc., Calgary, Canada [22] Filed: May 8, 1974 [21] Appl. No.: 467,972

3,598,369 8/1971 Yielding 254/106 Primary E.raminer-Othell M. Simpson Attorney, Agent, or Firm,lames A. Lamb 1 1 1 June 17, 1975 [57] ABSTRACT Apparatus for pulling drill pipe has four hydraulic legs which extend and retract surface engaging feet to raise and lower a frame. A drill pipe gripping mechanism is mounted to the frame and comprises a slip bowl with an inner surface tapering inwardly and downwardly and a plurality of wedge-shaped slips which have one surface tapered to engage the inner surface of the slip bowl and the other surface parallel to the axis of the slip bowl. The slips slide down to engage a drill pipe surface and the hydraulic legs are extended to pull the pipe upwards. A control ring is mounted to the frame for limited axial movement and connecting members connect each slip to the control ring. A plurality of smaller hydraulic cylinders are connected between the frame and the control ring so that when these cylinders are extended the control ring is raised to pull the slips upwardly and thus ensure the slips disengage the surface of the drill pipe before the four hydraulic legs are retracted for the next cycle.

7 Claims, 2 Drawing Figures APPARATUS FOR PULLING DRILL PIPE This invention relates to apparatus for pulling or recovering drill pipe.

The term drill pipe is used herein in a broad sense to mean a pipe or casing which has been drilled or pressed into the ground and is in engagement with a ground or earth formation In certain types of doublewalled drill pipe, the inner portion may be withdrawn from its position within the outer portion or casing. It is the outer portion or casing that would be pulled by the apparatus of this invention and the term drill pipe" is intended to include in its meaning such an outer portion or casing.

In the drilling of earth formations where at least portions of the formations are of unconsolidated deposits, it is common to use pulling apparatus to recover the drill pipe. The pulling apparatus has feet to support the apparatus in a level position with a gripping mechanism around the pipe. and hydraulic or mechanical jacks to raise and lower the gripping mechanism. In operation the jacks are lowered or retracted until the gripping mechanism is at its lowest operational position, then the jacks are raised or extended with the gripping mechanism engaging the drill pipe to pull the drill pipe upwards. The jacks are then lowered to repeat the cycle.

One well known type of gripping mechanism has a collar surrounding the pipe, and the collar has an inward surface which sloppes inwardly and downwardly. Several wedge shaped members, referred to as slips, are seated within the collar with one surface engaging the sloping surface of the collar. The wedge or slip has a shape such that its other surface is substantially parallel to the drill pipe. As the jacks are extended the slips tend to slip downwardly to grip the drill pipe and raise it. When the jacks are retracted or lowered, the collar moves downwards and the slips have a general tendency to ride upwards on the sloping collar surface to disengage the drill pipe so that the drill pipe is not moved downwards with the collar. The force with which the slips are pressed against the drill pipe is a considerable force and may cause the slips to deform the drill pipe locally, that is the force may cause the slips to imbed themselves slightly in the metal of the drill pipe. The slips may then not loosen when the jacks retract and the collar moves downwards.

The present invention provides a mechanism or arrangement in a drill pulling apparatus which disengages the wedges or slips or other gripping device prior to the jacks retracting and the collar moving downwards.

It is therefore an object of the invention to provide apparatus for pulling drill pipes which disengages the gripping mechanism before the mechanism is moved downwards.

In accordance with the invention there is provided apparatus for pulling drill pipe comprising a frame, a plurality of hydraulic cylinders mounted to said frame with the axes of said cylinders substantially parallel, each cylinder having a piston rod with a projecting end, a supporting surface-engaging foot mounted to said projecting end of each said piston rod, a slip bowl means mounted to said frame and having an axis parallel to the axes of said hydraulic cylinders, said slip bowl means having an inner surface tapering inwardly in a direction towards the surface-engaging feet, a plurality of slips having a wedge-shaped configuration, mounted within said slip bowl, means said slips having one surface tapered to engage said inner surface of said slip bowl means and the other surface substantially parallel to the axis of the slip bowl means for engagement with the outer surface ofa drill pipe, a control ring mounted for limited axial movement, a plurality of connecting members connecting each slip to said control ring. and means to cause axial movement of said control ring whereby said control ring may be moved in an axial direction away from said slip bowl means to cause said slips to move along the tapered surface of said slip bowl means to disengage the surface of a drill pipe.

The invention will be described with reference to the accompanying drawing in which:

FIG. 1 is a top view of apparatus according to the invention, and

FIG. 2 is a view taken along line 2-2 of FIG. 1.

Referring to the drawings the apparatus has four legs 10 which are mounted at one end to a frame 11 and at the other end to a frame 13. The frame 11 is at the upper end of the legs 10 when the apparatus is in operating position and the frame 13 is at the lower end of the legs. Each leg I0 comprises a hydraulic cylinder 12 with a central piston rod or shaft 14 extending from the lower end. The shafts 14 each terminate in a ball shaped member 15 to which is fastened a foot 16. That is there is a ball and socket connection between each shaft 14 and the respective foot 16 to permit limited tilting movement of the foot. As is well known in the art, the hydraulic cylinder is provided with an inlet an" outlet so that hydraulic fluid may be provided to the appropriate end of the cylinder to cause the piston with the piston rod to move inwardly or outwardly. For convenience this inward and outward movement of piston and piston rod is referred to as retracting or extending the cylinder.

The upper frame 11 joins the four legs and has a central member I7 to which is mounted a guide ring 18. The guide ring 18 has guide strips 20 on its inner surface. The size of the guide ring and strips may be changed to accommodate different sizes of drill pipe. The guide strips 20 terminate to form a generally cylindrical aperture as best seen in FIG. I, the aperture being slightly larger than the drill pipe which is to be pulled. The guide ring 18 and guide strips 20 serve to center the apparatus around a drill pipe.

The lower frame 13 joins the four legs and has mounted centrally thereof a slip bowl 21. The slip bowl 21 has a taper machined on its inner surface 22 so that the inner surface slopes inwardly and downwardly. The lower portion of slip bowl 21 may include guide plates 23 extending inwardly and terminating to form a generally cylindrical surface to aid in initial centering of the apparatus.

A plurality of slips 24 are mounted within the slip bowl. Each slip has an outer surface with a taper that conforms to the inner surface 22 of slip bowl 2]. When the slips are seated their inner surfaces 25 define a cylinder, that is the inner surfaces 25 are substantially parallel to the outer surface ofa drill pipe extending therethrough (not shown).

In FIG. 2 there is shown a filler ring 26 which fits inside slip bowl 2l. The filler ring 26 serves to decrease the working diameter of the slips so that the apparatus can be readily adapted to pull smaller pipe. It will be understood that the filler ring 26 is shown in FIG. 2 to illustrate the adaptation of the apparatus to various sizes and would not be required for pulling the maximum size of pipe for which it is designed.

A plurality of rods extend between upper frame 11 and lower frame 13 to serve as guides. A guide cylinder 31 is mounted on each rod 30 and is capable of limited sliding movement along rod 30. The guide cylin' ders 31 each have an arm 32 extending inwardly and secured to a control ring 33. Thus the control ring 33 is capable of limited longitudinal movement, that is of limited movement in a direction parallel to the axis of the drill pipe (not shown) to be pulled. The control ring 33 has an inwardly projecting upper collar 34 with a plurality of holes. A plurality of connecting members 35 extend through a respective one of the holes in collar 34 to a respective one of the slips 24. The connecting members 35 make a pivotal connection at 36 to the slip so that movement of connecting members 35 will not tend to affect the orientation of the slip as they cause the slip to slide upwardly within slip how] 21. A sphere 37 is mounted on the end of each connecting member 35 remote from the slip and on the other side of collar 34 from the slips 24. The spheres 37 are larger than the holes in collar 34 and seat in these holes whereby upward movement of control ring 33 causes upward movement (ie a withdrawal) of slips 24. It will of course be apparent that other means could be used to connect control ring 33 to the slips but the connec tion just described is convenient, A screw connection between the spheres 37 and the respective connecting members 35 permits easy assembly and disassembly and provides a convenient adjustment.

Four secondary hydraulic cylinders 40 are mounted at one end by a pin connection 4] to slip bowl 21 and the respective piston rod 42 makes a pin connection 43 with an arm 44 on control ring 33. Operation of secondary cylinders 40 by control of hydraulic fluid thereto will extend or retract the piston rods 42 to move the control ring 33 and slips 24 longitudinally.

It is believed that the operation of the apparatus will be apparent. The apparatus is placed around a bore hole with the guide ring 18 and slip bowl 2! aligned as closely as possible with the drill pipe to be pulled. The feet 16 conform to the ground surface. The hydraulic cylinders 12 and secondary hydraulic cylinders 40 are retracted. The slips 24 move downwards under the force of gravity until the inner surfaces engage the outer surface of the drill pipe. The hydraulic cylinders 12 or hydraulic jacks are then extended. The slip bowl moves upwards and the surface friction betwen slips 24 and the drill pipe tends to move the slips 24 into tighter engagement with the drill pipe which moves upwards with the slip bowl and associated members. When the hydraulic cylinders or jacks 12 are fully extended and prior to retracting them, the secondary hydraulic cylinders 40 are extended raising control ring 33 and forcibly moving slips 24 upwardly within slip bowl 21 to cause slips 24 to disengage the surface of the drill pipe. The hydraulic cylinders 12 are then retracted for the next cycle. and the secondary cylinders 40 are also retracted prior to the next cycle. The extension of cylinders l2 and subsequent retraction (with the associated operation of hydraulic cylinders 40 as described) is repeated until the pipe is withdrawn. It is customary during the pulling of a drill pipe to also use a derrick. A cable from the derrick is fastened to the end of the drill pipe, not to assist directly in the pulling action. but to ensure that the drill pipe does not slip downwards (as it might tend to do in certain types of earth formations) when the main cylinders are retracted and to support the upper section of drill pipe when it is disconnected. When a section of drill pipe is to be removed, the drill pipe is normally pulled upwards until a complete section is clear and the pulling apparatus remains engaged with the upper portion of the next section until the upper section is uncoupled and swung clear and the cable reattached to the next section of drill pipe.

I claim:

1. Apparatus for pulling drill pipe comprising a frame,

a plurality of jack means with surface-engaging feet for raising and lowering said frame with respect to said feet, slip bowl means mounted to said frame and having an inner surface tapering inwardly in a direction towards said feet,

a plurality of slips having a wedge-shaped configuration mounted within said slip bowl means, said slips having one surface tapered to engage said inner surface of said slip bowl means and the other surface arranged for engagement with the outer surface of a drill pipe.

a control member mounted for limited movement in a direction to and from said slip bowl means,

plurality of connecting members connecting each slip to said control member, and

means to move said control member away from said slip bowl means to cause said slips to move along said tapered surface of said slip bowl means for effecting disengagement of said slips from a drill pipe.

2. Apparatus for pulling drill pipe comprising a frame,

a plurality of hydraulic cylinders mounted to said frame with the axes of said cylinders substantially parallel, each cylinder having a piston rod with a projecting end,

a supporting surface-engaging foot mounted to said projecting end of each said piston rod,

slip bowl means mounted to said frame and having an axis parallel to the axes of said hydraulic cylinders, said slip bowl means having an inner surface tapering inwardly in a direction towards the surfaceengaging feet,

a plurality of slips having a wedge-shaped configuration, mounted within said slip bowl means. said slips having one surface tapered to engage said inner surface of said slip bowl means and the other surface substantially parallel to the axis of the slip bowl means for engagement with the outer surface of a drill pipe,

control ring mounted for limited axial movement,

plurality of connecting members connecting each slip to said control ring, and

means to cause axial movement of said control ring whereby said control ring may be moved in an axial direction away from said slip bowl means to cause said slips to move along the tapered surface of said slip bowl means to disengage the surface of a drill pipe.

3. Apparatus as defined in claim 2 in which each said surface-engaging foot is pivotally mounted to the projecting end of the respective piston rod.

5. Apparatus as defined in claim 2 in which said slip bowl means includes a slip bowl and an inner filler ring sitting within said slip bowl providing said inner surface, said filler ring adapting the apparatus for different sizes of drill pipe.

6. Apparatus as defined in claim 2, in which said means to cause axial movement of said control ring comprises a plurality of hydraulic cylinders including extendable piston rods mounted between said frame and said control ring.

7. Apparatus for pulling drill pipe comprising a frame,

four hydraulic cylinders mounted to said frame with their axes substantially parallel, each cylinder having a piston rod with a projecting end,

a supporting surface-engaging foot pivotally mounted on said projecting end of each piston rod,

said hydraulic cylinders including means for extending and retracting said piston rods to raise and lower said frame,

a slip bowl mounted to said frame and having an axis parallel to the axes of said cylinders, said slip bowl having an inner surface tapering linearly inwardly in a direction towards said surface-engaging feet,

a plurality of slips having a wedge-shaped configuration, mounted within said slip bowl, said slips having one surface tapered to engage said inner surface of said slip bowl and the other surface substantially parallel to the axis of said slip bowl, said other surfaces of said slips defining a cylindric opening for receiving a drill pipe,

21 control ring mounted to said frame for limited axial movement and positioned above said slip bowl with its open central portion aligned with the axis of said slip bowl whereby a drill pipe may pass therethrough, said control ring having a plurality of holes spaced therearound one for each slip,

a connecting member for each slip connected at one end to said slip and extending through a respective hole in said control ring,

a retaining member on the other end of each said connecting member of a size larger than the re spective hole for engaging said control ring as said control ring moves axially away from said slip bowl to move said slips upwardly in said slip bowl, and plurality of hydraulic cylinders including a piston rod mounted between said frame and said control ring to move said control ring causing said slips to move upwardly on the tapered surface of said slip bowl to disengage the surface of a drill pipe. 

1. Apparatus for pulling drill pipe comprising a frame, a plurality of jack means with surface-engaging feet for raising and lowering said frame with respect to said feet, slip bowl means mounted to said frame and having an inner surface tapering inwardly in a direction towards said feet, a plurality of slips having a wedge-shaped configuration mounted within said slip bowl means, said slips having one surface tapered to engage said inner surface of said slip bowl means and the other surface arranged for engagement with the outer surface of a drill pipe, a control member mounted for limited movement in a direction to and from said slip bowl means, a plurality of connecting members connecting each slip to said control member, and means to move said control member away from said slip bowl means to cause said slips to move along said tapered surface of said slip bowl means for effecting disengagement of said slips from a drill pipe.
 2. Apparatus for pulling drill pipe comprising a frame, a plurality of hydraulic cylinders mounted to said frame with the axes of said cylinders substantially parallel, each cylinder having a piston rod with a projecting end, a supporting surface-engaging foot mounted to said projecting end of each said piston rod, slip bowl means mounted to said frame and having an axis parallel to the axes of said hydraulic cylinders, said slip bowl means having an inner surface tapering inwardly in a direction towards the surface-engaging feet, a plurality of slips having a wedge-shaped configuration, mounted within said slip bowl means, said slips having one surface tapered to engage said inner surface of said slip bowl means and the other surface substantially parallel to the axis of the slip bowl means for engagement with the outer surface of a drill pipe, a control ring mounted for limited axial movement, a plurality of connecting members connecting each slip to said control ring, and means to cause axial movement of said control ring whereby said control ring may be moved in an axial direction away from said slip bowl means to cause said slips to move along the tapered surface of said slip bowl means to disengage the surface of a drill pipe.
 3. Apparatus as defined in claim 2 in which each said surface-engaging foot is pivotally mounted to the projecting end of the respective piston rod.
 4. Apparatus as defined in claim 2 in which said slip bowl means is a slip bowl in which said inner surface is tapered linearly.
 5. Apparatus as defined in claim 2 in which said slip bowl means includes a slip bowl and an inner filler ring sitting within said slip bowl providing said inner surface, said filler ring adapting the apparatus for different sizes of drill pipe.
 6. Apparatus as defined in claim 2, in which said means to cause axial movement of said control ring comprises a plurality of hydraulic cylinders including extendable piston rods mounted between said frame and said control ring.
 7. Apparatus for pulling drill pipe comprising a frame, four hydraulic cylinders mounted to said frame with their axes substantially parallel, each cylinder having a piston rod with a projecting end, a supporting surface-engaging foot pivotally mounted on said projecting end of each piston rod, said hydraulic cylinders including means for extending and retracting said piston rods to raise and lower said frame, a slip bowl mounteD to said frame and having an axis parallel to the axes of said cylinders, said slip bowl having an inner surface tapering linearly inwardly in a direction towards said surface-engaging feet, a plurality of slips having a wedge-shaped configuration, mounted within said slip bowl, said slips having one surface tapered to engage said inner surface of said slip bowl and the other surface substantially parallel to the axis of said slip bowl, said other surfaces of said slips defining a cylindric opening for receiving a drill pipe, a control ring mounted to said frame for limited axial movement and positioned above said slip bowl with its open central portion aligned with the axis of said slip bowl whereby a drill pipe may pass therethrough, said control ring having a plurality of holes spaced therearound one for each slip, a connecting member for each slip connected at one end to said slip and extending through a respective hole in said control ring, a retaining member on the other end of each said connecting member of a size larger than the respective hole for engaging said control ring as said control ring moves axially away from said slip bowl to move said slips upwardly in said slip bowl, and a plurality of hydraulic cylinders including a piston rod mounted between said frame and said control ring to move said control ring causing said slips to move upwardly on the tapered surface of said slip bowl to disengage the surface of a drill pipe. 